Vacuum tube



Aug. 23, 1932.

c. v. LITTON VACUUM TUBE Filed Oct. 22, 1929 INVENTOR Char/es 1/. L/ffmATTORN EY Patnted 23, 1932 UNITED STATES PATENT OFFICE-57.:

CHARLES v. matron, or REDWOOD crcrzcALIFonmA, nssieivon rornnnnnr.'rntn- GRAPH COMPANY, or SAN FORNIA Application filed ottober 22, 1929.Serial No. 401,398.

This invention relates to vacuum tubes and their manufacture andparticularly to the construction of lowpower tubes such as are u, usedin radio receiving sets. p

The broad object of the invention is to reduce the cost of manufacturingsmall vacuum tubes. This is accomplished, first, by reducing. thestructure for supporting the elec- M trodes to wires rising'from thepress of the d tube and reinforcing these Wires, where necessary, withtrough shaped members fitting over the edges'of the press; second, byutilizing a getter support of sheet metal'placed w non-adjacent and atan angle to the anode elements, whereby during evacuation the anodes canbe heated by high frequency induc tion without heating the gettersupport,

although the latter may be heated when it is i desired to flash thegetter, by shifting the tube 26 into a different position with respectto the high frequency exciting coil. This and other features of theinvention will be explained in the following description in connectionwith the drawing in which:

Fig. 1 is a view of a complete electrode as sembly'with part of theanode cut away to show the grid and cathode structure.

Fig. 2 is an edge section through the electrode structure.

Fig. 3 is a section through the press of the tube. Y t

Fig. i is a view of one of the blanks from which the anode isconstructed. 7

Fig. 5 is a top view of the grid structure.

Fig. 6 is a side view of the grid structure.

Fig. 7 is a side view of the cathode structure.

Fig. 8 is a side view of an alternative oath odestructure and,

Fig. 9 is a schematic drawing showing the method of heating the anode ofthe tube by high frequency induction; I

In Fig. 1 an electrode structure is depicted which comprises an anode 1,grid elements 15, filamentary cathode 2, and means for supporting thesevarious elements.

The cathode assembly is shown to best advantage in Fig. 7. The cathodeitself consists of a filament 2 in the shape of an inverted W, theextremities of which are secured supports 11 or cross member 28 or both,may

} vacuum TUBE to supporting wires 25 rising from the press of the tube,and the mid point'of which is welded to acjentral rod or wire 9 alsorising from the press. To provide-for expansion and contraction of thefilament 2 the upper' loops are supported by resilient wires 11 whichare secured to the upper end of rod 9, p and at the same timeinsulated:therefrom, by a glass bead 10. Bead-10, in addition to servingas an insulating attaching means btween element 11 and rod-9, servestospace the cathode structure from the grid, since the bead 10 isflattened as shown in Fig. Qland fits between elongated grid bars 16. iIn Fig. 8 an alternative cathodestructure is disclosed in whichtwo glassbeads-secure the supports to a cross member 28, which is welded atitsmid point to the top of rod 9. In this embodiment of the inventioneither be of resilient material to tension the filament. It is preferredto reduce the overall height of this cathode structure so that itwilllie entirely within the grid'structure.

' The grid structure as'illustrated in Figs. 5 and 6 consists of aplurality of hairpin shaped elements 15 and straight extended centerelements 16. These vertical elements. are weldedto a lower continuousframe mem ber3, which is welded to supporting wires" rising from thepress of thetube, and to a pair of straight frame members26 nearthe'top. The straight bars 16 are provided to permit' the filamentsupporting and aligning bead '10 shown in Figs. 1, 2, and 7, to extendabove the topsof the hairpin elements 15, but this is not essential, andthe cathode as-. semblies shown ineither Figs/.7 or 8, may beproportioned to lie entirely within the grid, in which case all the gridbars may be of the hairpin type. I I The anode consists of tworectangular. plates 1 having. integral tabs 14%. The two plates'aresecured together to form arigid assembly by bending the tabs 14 of oneplate around and welding them'to the otherplate as shown in Figs. 1 and2'. Theistructure is supported in position in the tube by two. wiresfirising from the press and welded to the two Plates rspflctively- Theanode supf i TI portingelements 4, if chosen of a convenient size forsealing into the press of the tube, lack the'strength necessary toprevent lateral displacement of the anodes when the tube is subjected toviolent shocks in shipment or handling. To prevent, bending of elements4 they are therefore reinforced with clamps 5, which as shown in Figs.1, 2, and 3, are shaped to fit snugly over the edge of the 10 13. Inpractice, the clamps eare shaped to fit the press 8 but do not grip ittightly, since 7 their only function is to prevent lateral dis of someother material such as nickel and'be welded to short elements 27ofplatinum as shown in Fig.1. With this sort of construc- 85 tion, thewelded joint may lie withinthe press, and although a tight seal is onlyob tained between the glass and the portion27,

- this has been found to provide a structure which is satisfactory. I A

In order to remove the last traces of gas and'water vapor from atubeduring evacuationit is common practice to vaporize a getteringmaterialsuch as magnesium within the tube while it is being pumped. Itis also necessay to heat the electrodes, particularly the anode, duringevacuation and it is preferable'to. vaporize the getter materialsubsequent to the heating of the anode. To make possible a thoroughheating of the anode Without-affecting the getter, the latter isattached to a disk 6 supported by a wire 12 secured to the centercathode support 9. In

' 1, the getter material'is shown as a rectangue lar. piece of magnesium7, but other materials planes, large eddy currents are set up in theanodes sufficient to heat them to a desired temperature. The gettersupporting disk 6, how-- ever, being of smaller area and, what ismoreimportant, being mounted in a plane at an 7 angle to the planes of thecoils 21 and 22,.has relatively little current induced therein and doesnot get hot'enough to vaporize the gettering material on its surface.When the anodes are sufiiciently freed of gas, the tube.

is flashed by twisting it within the coils, or by twisting thecoilsabout the tube, to bring pressS and are welded to supports 4 atpoints analloy having a coeflicient of expansion may be used. The disk 6 is setatan angle to the disk 6 in a plane parallel with the planes of thecoils, under which conditions the disk is heated to a high temperatureand the getter vaporized. I 7 1 A further advantage of placing thegetter support in the particular position and at the angle shown is thatthe getter material, after fia'shing, is deposited largely on the wallof the. tube instead of on the electrodes. It has been found that'somecathode materials are deleteriously affected foreign matter.

I claim:

1. A vacuum tube mount comprising a byja small deposit of *press, ananode, supporting elements sealed into said press and attached to saidanode and serving ,as thesole supporting means of said anode, andreinforcing means secured to said supports and contacting with 'the exwment of said anode.

terior surface of said press'to resist displace- 2. A vacuum'tube mountcomprising a fiat tened press, an anode, supporting wires sealed intosaid press'and attachedto said anode and serving as the sole supportingmeans for said" anode, and reinforcmg means comprising a troughshaped,'sheet-metal member "fitting over theedge of said press andsecured to one of said supporting wires. V

3. A vacuum tube mount comprising afiat- 'tened press havingsubstantially parallel sides, an electrode, a supporting wire sealed ntosa d press and attached to said electrode and reinforcing means for saidsupporting wire attached thereto and rigidly positioned against movementperpendicular to the parallel surfaces of said press, by contact withsaid surfaces. r

4. A vacuum anodehaving two opposed parallel portions, a grid positionedbetween said anode portions comprising a plurality of vertical barslying two planes, a cathode within said grid, and cathode supportingmeans comprising a body of insulating material in contact with, but notsecured to, grid bars lying in said two planes. i

t 5. A vacuum tube mount comprising a pair of anode elements, agridpositioned between said anode elements comprising a plurality ofvertical bars lying in two parallel planes,

- some of which extend above the rest, affila- In testimony whereof,have hereunto set' my hand.

tube mount comprising an

